A method for determining the position of the rotation axis using an absolute position target

Abstract

This invention relates to the field of image measurement and coordinate measurement technology, specifically to a method for determining the position of a rotation axis using an absolute position target, comprising the steps of: adjusting the spatial attitude of the absolute position target, calibrating the relative positional relationship between the absolute position target and the dual-axis rotary table, and determining the reference coordinate system O. S -X S Y S Z S Origin O S X S0 Coordinate components determine the reference coordinate system O S -X S Y S Z S Origin O S Y S0 Coordinate components determine the reference coordinate system O S -X S Y S Z S Origin O S Z S0 Coordinate components are used to calculate the position O of the rotation axis of the dual-axis rotary table. B and O C The purpose of this method for determining the position of the rotation axis using an absolute position target is to solve the problem of reduced performance of a two-axis rotary table in a five-axis image coordinate measuring system due to the influence of the power-on and zero-return states of a three-coordinate measuring machine.

Description

Technical Field

[0001] This invention relates to the field of image measurement and coordinate measurement technology, specifically to a method for determining the position of a rotation axis using an absolute position target. Background Technology

[0002] Currently, measurement technology and related disciplines have made significant progress. Image measurement, as a non-contact measurement technology, can solve many problems that are difficult or impossible to solve with traditional measurement methods, and has been widely used in industrial settings. Image measurement applies computer vision or machine vision technology to the measurement and positioning of geometric features, using images acquired by industrial cameras as a means of information acquisition. It not only has the advantages of high efficiency, ease of operation, strong adaptability, and high reliability of non-contact measurement methods, but also features low cost, flexibility, rich information, and strong real-time performance.

[0003] Meanwhile, to better address the image measurement challenges of industrial products or mechanical parts with complex structures, shapes, and surface features, industrial cameras need to possess a greater degree of freedom of movement to enhance the flexibility, versatility, and comprehensiveness of the image measurement system. Therefore, an industrial camera was integrated with a coordinate measuring machine (CMM) and a two-axis position turntable to design and construct a novel five-axis image coordinate measurement system with three linear axes and two rotary axes. The industrial camera acts as the front-end sensor, acquiring measurement data of the object under test. The CMM serves as the moving platform for the industrial camera, tracking its measurement trajectory. The two-axis position turntable, in conjunction with the system, enables measurements of the object from different orientations, obtaining complete measurement data and improving measurement efficiency.

[0004] In this novel five-axis image coordinate measurement system, to truly achieve five-axis image coordinate measurement functionality, the positions or three-dimensional coordinates of the two rotation axes in the machine coordinate system must be calibrated before use. This is necessary to establish a rotation coordinate system, allowing measurement data obtained at different angular positions to be converted into a unified spatial coordinate system, thus enabling multi-axis measurement. However, for coordinate measuring machines used to achieve linear motion and coordinate positioning along the X, Y, and Z axes, each linear axis is typically equipped with incremental or relative grating rulers to reduce hardware costs while meeting functional and accuracy requirements and ensuring compatibility with the controller. For this type of grating ruler, there is no absolute zero point. The zero point must be set by triggering the limit switch. Therefore, the reading of the reading head at any position is not fixed, but is related to the reading of the set zero point or preset point. The reading at any position is displayed by counting the increment and decrement pulses from that point (zero point or preset point). Most coordinate measuring machines use incremental grating rulers, and most coordinate measuring machines need to be returned to zero after powering on to set the grating zero point (machine coordinate system zero point).

[0005] During the homing process after a coordinate measuring machine (CMM) is powered on, its X, Y, and Z axes move towards the designated endpoint of their travel according to a defined order and direction. Upon reaching the endpoint, it searches backward. Once the first zero-position marker of the grating scale is found, the grating count is reset to zero. This point is the zero point of the machine coordinate system in this homing state. Therefore, the zero point of the CMM's machine coordinate system is affected by the homing process and the limit switches, resulting in zero-point deviation and drift. This means that the homing state after each power-on is different. Consequently, the rotation axis position of the two-axis position turntable calibrated after a particular power-on and homing process cannot be directly applied to subsequent measurement tasks. Only after the next power-on and homing process, through coordinate correction or recalibration, can the new relative positional relationship between the two-axis position turntable and the CMM's machine coordinate system zero point be determined in this state. Only then can this relationship be applied to subsequent measurement processes to obtain accurate multi-view measurement data. This makes the operation and use of the five-axis image coordinate measurement system extremely cumbersome and inconvenient, and significantly reduces its efficiency.

[0006] Therefore, the inventors have provided a method for determining the position of the rotation axis using an absolute position target. Summary of the Invention

[0007] (1) Technical problems to be solved

[0008] This invention provides a method for determining the position of the rotation axis using an absolute position target, which solves the technical problem that the position of the dual-axis rotary table in a five-axis image coordinate measurement system is affected by the power-on and zero-return states of the three-coordinate moving platform, resulting in reduced performance.

[0009] (2) Technical solution

[0010] This invention provides a method for determining the position of a rotation axis using an absolute position target. The five-axis image coordinate measuring device with an absolute position target includes a five-axis image coordinate measuring device, a target device mounted on the five-axis image coordinate measuring device, and a protective cover for the target device. The five-axis image coordinate measuring device includes a worktable, a dual-axis rotary table, a clamping fixture, a three-coordinate moving platform, and an industrial camera. The dual-axis rotary table and the three-coordinate moving platform are both mounted on the worktable. The clamping fixture is mounted on the table surface of the dual-axis rotary table. The industrial camera is mounted on the Z-axis moving end of the three-coordinate moving platform. The target device includes an absolute position target.

[0011] The method includes the following steps:

[0012] Adjust the spatial attitude of the absolute position target;

[0013] The relative positions between the absolute position target and the dual-axis rotary table are calibrated, and the front surface, side surface, and upper surface of the absolute position target are determined to be relative to the pitch coordinate system O. B -X B Y B Z B Origin B and azimuth coordinate system O C -X C Y C Z C Origin C Spacing ΔX in the X, Y, and Z axes BS and ΔX CS ΔY BS and ΔY CS ΔZ BS and ΔZ CS ;

[0014] Move the industrial camera until the front surface of the absolute position target is on the object-side focal plane of the industrial camera, then determine the reference coordinate system O based on the grating ruler reading of the X-axis linear motion. S -X S Y S Z S Origin O S X S0 Coordinate components;

[0015] Lock the X-axis and move the industrial camera along the Y-axis. When the front edge of the absolute position target appears in the field of view of the industrial camera, determine the reference coordinate system O based on the grating ruler reading on the Y-axis linear motion axis and the pixel distance between the image coordinates of the front edge of the absolute position target and the image center coordinates. S -X S Y S Z S Origin O S Y S0 Coordinate components;

[0016] Lock the X-axis and move the industrial camera along the Z-axis. When the edge of the absolute position target appears in the field of view of the industrial camera, determine the reference coordinate system O based on the grating ruler reading of the Z-axis linear motion and the pixel distance between the image coordinates of the edge of the absolute position target and the image center coordinates. S -X S Y S Z S Origin O S Z S0 Coordinate components;

[0017] Based on ΔX BS and ΔXCS ΔY BS and ΔY CS ΔZ BS and ΔZ CS and X S0 Coordinate components, Y S0 Coordinate components, Z S0 Coordinate components are used to obtain the position O of the rotation axis of the dual-axis rotary table. B and O C .

[0018] Furthermore, adjusting the spatial attitude of the absolute position target specifically involves:

[0019] After powering on and returning to zero, the target device is installed on the workbench, and the spatial attitude and orientation of the absolute position target are adjusted so that the front surface of the absolute position target is parallel to the YOZ plane and the upper surface of the absolute position target is parallel to the XOY plane, thus fixing the state of the absolute position target and keeping it unchanged.

[0020] Furthermore, the target device also includes a base and an attitude adjustment mechanism. The base is fixed on the worktable, the attitude adjustment mechanism is installed on the base, and the absolute position target is fixed to the attitude adjustment mechanism.

[0021] Furthermore, the attitude adjustment mechanism includes a one-dimensional yaw stage A, a one-dimensional yaw stage B, a one-dimensional rotary stage, multiple locking nuts and multiple adjusting handles, and the absolute position target is installed on the one-dimensional rotary stage;

[0022] The one-dimensional tilting stage A and the one-dimensional tilting stage B are stacked and installed in sequence, and are respectively used to adjust the rotation angle α of the absolute position target around the X-axis and the rotation angle β around the Y-axis under the drive of the corresponding adjustment handle, and are locked in position by the corresponding locking nut.

[0023] The one-dimensional rotary table is superimposed on the one-dimensional oscillating table A or the one-dimensional oscillating table B and is used to adjust the rotation angle γ of the absolute position target around the Z-axis under the drive of the corresponding adjustment handle, and is locked in position by the corresponding locking nut.

[0024] Furthermore, the absolute position target is made of cemented carbide steel and is cubic in shape.

[0025] Furthermore, the five-axis image coordinate measuring device with an absolute position target also includes a target device protective cover, which is installed on the worktable and covers the target device.

[0026] Furthermore, the protective cover of the target device is a transparent cubic hollow shell.

[0027] Furthermore, a window is provided on the front surface of the protective cover of the target device.

[0028] Furthermore, the industrial camera includes an industrial camera, a telecentric lens, and a light source. The telecentric lens is mounted in the lens interface at the front end of the industrial camera, and the light source is mounted at the front end of the telecentric lens.

[0029] Furthermore, the light source is the LED ring light source.

[0030] (3) Beneficial effects

[0031] In summary, this invention, based on the characteristics of industrial cameras, designs an absolute position target with planar features and installs it on the worktable of a five-axis image coordinate measuring device. The industrial camera acquires the position of the absolute position target in the machine coordinate system under different power-on and homing states, and then fuses it with the calibrated relative position relationship data to indirectly obtain the position of the dual-axis rotary table in the machine coordinate system under these states. This improves the efficiency of the five-axis image coordinate measuring device and has the advantages of simple principle, easy implementation, and simple calculation method, making it of great practical application value. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart illustrating a method for determining the position of a rotation axis using an absolute position target, as provided in an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of a five-axis image coordinate measuring device with an absolute position target provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the target device of a five-axis image coordinate measuring device with an absolute position target provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the attitude adjustment mechanism of a target device provided in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the absolute position target of a target device provided in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the structure of an industrial camera with an absolute position target for five-axis image coordinate measurement, provided in an embodiment of the present invention.

[0039] Figure 7 This is a schematic diagram of the structure of a protective cover for a target device provided in an embodiment of the present invention;

[0040] Figure 8 This is a ΔX provided in an embodiment of the present invention. CS (ΔX BS ) and ΔZ CS (ΔZ BS A schematic diagram;

[0041] Figure 9 This is a ΔY provided in an embodiment of the present invention. CS (ΔY BS A schematic diagram;

[0042] Figure 10 This is a schematic diagram of an absolute position target with its front edge within the field of view of an industrial camera, provided by an embodiment of the present invention.

[0043] Figure 11 This is a schematic diagram of an image provided by an embodiment of the present invention, showing that the edge of an absolute position target is within the field of view of an industrial camera.

[0044] In the picture:

[0045] 1-Five-axis image coordinate measuring device; 11-Worktable; 12-Dual-axis rotary table; 13-Clamping fixture; 14-Three-coordinate moving platform; 15-Industrial camera; 151-Industrial camera; 152-Telecentric lens; 153-Light source; 2-Target device; 21-Base; 22-Attitude adjustment mechanism; 221-One-dimensional tilting stage A; 222-One-dimensional tilting stage B; 223-One-dimensional rotary table; 224-Locking nut; 225-Adjusting handle; 23-Absolute position target; 231-Front surface of absolute position target; 232-Upper surface of absolute position target; 233-Side surface of absolute position target; 234-Upper edge of absolute position target; 235-Front edge of absolute position target; 3-Target device protective cover; 31-Front surface of protective cover; 311-Window. Detailed Implementation

[0046] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. That is, the present invention is not limited to the described embodiments, and any modifications, substitutions and improvements to the parts, components and connection methods are covered without departing from the spirit of the present invention.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0049] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "install" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Figure 1 This is a flowchart illustrating a method for determining the position of a rotation axis using an absolute position target, as provided in an embodiment of the present invention. Figure 2 , Figure 3 , Figure 7 As shown, the five-axis image coordinate measuring device with an absolute position target includes a five-axis image coordinate measuring device 1, a target device 2 installed on the five-axis image coordinate measuring device 1, and a target device protective cover 3. The five-axis image coordinate measuring device 1 includes a worktable 11, a dual-axis rotary table 12, a clamping fixture 13, a three-coordinate moving platform 14, and an industrial camera 15. The dual-axis rotary table 12 and the three-coordinate moving platform 14 are both installed on the worktable 11. The clamping fixture 13 is installed on the table surface of the dual-axis rotary table 12. The industrial camera 15 is installed on the Z-axis moving end of the three-coordinate moving platform 14. The target device 2 includes an absolute position target 23.

[0051] The method includes the following steps:

[0052] S100, Adjust the spatial attitude of the absolute position target 23.

[0053] Specifically, after powering on and returning to zero, the target device 2 is installed on the workbench 11, and the spatial attitude and orientation of the absolute position target 23 are adjusted so that the front surface 231 of the absolute position target is parallel to the YOZ plane and the upper surface 232 of the absolute position target is parallel to the XOY plane, thus fixing the state of the absolute position target 23 and keeping it unchanged.

[0054] S200. Calibrate the relative position between the absolute position target 23 and the dual-axis rotary table 12, and determine the relative positions of the front surface 231, side surface 233, and upper surface 232 of the absolute position target with respect to the pitch coordinate system O. B -X B Y B Z B Origin B and azimuth coordinate system O C -X C Y C Z C Origin C Spacing ΔX in the X, Y, and Z axes BS and ΔX CS ΔY BS and ΔY CS ΔZ BS and ΔZ CS .

[0055] Specifically, a dial indicator, inductive micrometer, or industrial camera 15 is used as a calibration tool, and the calibration process determines: such as Figure 8 As shown, the front surface 231 of the absolute position target is aligned with the pitch coordinate system O. B -X B Y B Z B Origin B and azimuth coordinate system O C -X C Y C Z C Origin C Spacing ΔX along the X-axis BS and ΔX CS ;like Figure 9 As shown, the absolute position target side surface 233 is respectively with O B and O C Spacing ΔY along the Y-axis BS and ΔY CS ;like Figure 8 As shown, the upper surface 232 of the absolute position target is respectively with O B and O C Spacing ΔZ along the Z-axis BS and ΔZ CS .

[0056] S300, mobile industrial camera 15, when the front surface 231 of the absolute position target is on the object-side focal plane of the industrial camera 15, determines the grating ruler reading of the X-axis linear motion as the reference coordinate system O. S -X S Y S Z S Origin OS X S0 Coordinate components.

[0057] Specifically, the X, Y, and Z axes of the five-axis image coordinate measuring device 1 are controlled to move the industrial camera 15, so that the front surface 231 of the absolute position target enters the field of view of the industrial camera 15. The focus range and step size in the X-axis direction are set, and automatic focusing is performed to ensure that the industrial camera 15 is correctly focused on the front surface 231 of the absolute position target. At this time, the front surface 231 of the absolute position target is on the object-side focal plane of the industrial camera 15. The grating ruler readings of the three linear motion axes X, Y, and Z at this time are recorded as (X1, Y1, Z1), and the O is calculated. S X S0 The coordinate components are defined by the following formula:

[0058] X S0 =X1 (1)

[0059] S400. Lock the X-axis and move the industrial camera 15 along the Y-axis. When the front edge 235 of the absolute position target appears in the field of view of the industrial camera 15, determine the reference coordinate system O based on the grating ruler reading of the Y-axis linear motion and the pixel distance between the image coordinates of the front edge 235 of the absolute position target and the image center coordinates. S -X S Y S Z S Origin O S Y S0 Coordinate components.

[0060] Specifically, the X-axis is locked, causing the industrial camera 15 to move along the positive or negative Y-axis until the front edge 235 of the absolute position target appears in the field of view of the industrial image probe 15, such as... Figure 10 As shown, the image at this moment is acquired and the grating ruler readings of the three linear motion axes X, Y, and Z are recorded as (X2, Y2, Z2) (X2 = X1). Then, the image coordinates of the absolute position of the target's front edge 235 in the image are extracted through image processing, and the pixel distance l between it and the image center coordinates is calculated. a (Unit: pixel), then multiplied by the pixel size equivalent K on the focal plane (unit: mm / pixel) to obtain the pixel distance l. a Converted to physical distance 'a' (unit: mm), that is:

[0061] a=K·l a (2)

[0062] Solve O S Y S0 The coordinate components are defined by the following formula:

[0063] Y S0=Y2-a (3)

[0064] S500, lock the X-axis and move the industrial camera 15 along the Z-axis. When the edge 234 on the absolute position target appears in the field of view of the industrial camera 15, determine the reference coordinate system O based on the grating ruler reading of the Z-axis linear motion and the pixel distance between the image coordinates of the edge 234 on the absolute position target and the image center coordinates. S -X S Y S Z S Origin O S Z S0 Coordinate components.

[0065] Specifically, continue locking the X-axis, causing the industrial camera 15 to move along the positive Z-axis until the edge 234 of the absolute position target appears in the field of view of the industrial camera 15, such as... Figure 11 As shown, the image at this moment is acquired and the grating ruler readings of the three linear motion axes X, Y, and Z are recorded as (X3, Y3, Z3) (X3 = X1). Then, the image coordinates of the absolute position of the target edge 234 in the image are extracted through image processing, and the pixel distance l between it and the image center coordinates is calculated. b Then multiply it by the pixel size equivalent K on the focal plane to increase the pixel distance l. b Converted to physical distance b, that is:

[0066] b = K·l b (4)

[0067] Solve O S Z S0 The coordinate components are defined by the following formula:

[0068] Z S0 =Z3-b (5)

[0069] S600, based on ΔX BS and ΔX CS ΔY BS and ΔY CS ΔZ BS and ΔZ CS and X S0 Coordinate components, Y S0 Coordinate components, Z S0 Coordinate components are used to obtain the position O of the rotation axis of the dual-axis rotary table 12. B and O C .

[0070] Specifically, the reference coordinate system O is determined through the above steps. S -X S Y S Z SO of the coordinate system S Three-dimensional coordinates (X, Y, Z) in the machine coordinate system O-XYZ S0 ,Y S0 Z S0 Based on the spacing value ΔX determined through the calibration process in step S200. BS ΔY BS ΔZ BS ΔX CS ΔY CS and ΔZ CS Solve for O in this state B Three-dimensional coordinates in O-XYZ (X B0 ,Y B0 Z B0 ) and O C Three-dimensional coordinates in O-XYZ (X C0 ,Y C0 Z C0 The formulas are as follows:

[0071]

[0072]

[0073] In the above formula, "+" and "-" need to be specifically determined based on the actual relative positional relationship between the dual-axis rotary table 12 and the absolute position target 23 in terms of up and down, left and right, and front and back.

[0074] If the target device 2 is not disassembled and the relative positional relationship between the absolute position target 23 and the dual-axis rotary table 12 remains unchanged, then the spacing value ΔX BS ΔY BS ΔZ BS ΔX CS ΔY CS and ΔZ CS Without changing the initial state, after the next power-on and zeroing process, simply perform steps S300, S400, S500, and S600 to calculate the rotation center O of the dual-axis rotary table under this power-on and zeroing state. B and O C The three-dimensional coordinates are obtained, thus completing the initialization of the five-axis image coordinate measuring device 1, and applied to the subsequent measurement process to obtain correct multi-view measurement data.

[0075] As an optional implementation method, such as Figure 3 As shown, the target device 2 also includes a base 21 and an attitude adjustment mechanism 22. The base 21 is fixed on the worktable 11, the attitude adjustment mechanism 22 is installed on the base 21, and the absolute position target 23 is fixed to the attitude adjustment mechanism 22.

[0076] Specifically, the five-axis image coordinate measuring device 1 has five motion axes: three linear motion axes X, Y, and Z, and two rotary motion axes B and C. The three linear motion axes X, Y, and Z are perpendicular to each other and integrated together, implemented by a three-coordinate moving platform 14; the two rotary motion axes B and C are perpendicular to each other and integrated together, implemented by a dual-axis rotary table 12. The rotation angle range of the B axis is -90° to +90°, and the rotation angle range of the C axis is 0° to 360°.

[0077] like Figure 2 As shown, the three-coordinate moving platform 14 is mounted on the worktable 11. Each linear axis is equipped with an air-bearing guide rail and a high-precision incremental grating ruler, thereby ensuring the smoothness of movement and displacement accuracy of each linear axis. The dual-axis rotary table 12 is fixed on the worktable 11. Through mechanical alignment and adjustment, the B-axis direction is made parallel to the Y-axis direction, and the C-axis direction is made parallel to the Z-axis direction. The clamping fixture 13 is mounted on the table surface of the dual-axis rotary table 12 for clamping and positioning the measured part.

[0078] As an optional implementation, the attitude adjustment mechanism 22 includes a one-dimensional tilting stage A221, a one-dimensional tilting stage B222, a one-dimensional rotary stage 223, a plurality of locking nuts 224 and a plurality of adjusting handles 225, and an absolute position target 23 is mounted on the one-dimensional rotary stage 223.

[0079] One-dimensional pendulum stage A221 and one-dimensional pendulum stage B222 are stacked and installed in sequence, and are respectively used to adjust the rotation angle α of the absolute position target 23 around the X-axis and the rotation angle β around the Y-axis under the drive of the corresponding adjustment handle 225, and are locked in position by the corresponding locking nut 224.

[0080] A one-dimensional rotary table 223 is superimposed on a one-dimensional oscillating table A221 or a one-dimensional oscillating table B222 and is used to adjust the rotation angle γ of the absolute position target 23 around the Z-axis under the action of the corresponding adjusting handle 225, and is locked in position by the corresponding locking nut 224.

[0081] Specifically, such as Figure 4 As shown, since there are three tilting platforms and a rotating platform, three locking nuts 224 and three adjusting handles 225 are correspondingly set. The one-dimensional tilting platform A221, the one-dimensional tilting platform B222 and the one-dimensional rotating platform 223 are all equipped with corresponding locking nuts 224 and adjusting handles 225. In order to realize the tilting motion of the one-dimensional tilting platform A221 and the one-dimensional tilting platform B222, the contact surface between the one-dimensional tilting platform A221 and the base 21 is set as an arc surface, and the contact surface between the one-dimensional tilting platform A221 and the one-dimensional tilting platform B222 is set as an arc surface.

[0082] The one-dimensional tilting stage A221 and B222 are adjusted to a one-dimensional angle within the range of -30° to +30° via their respective adjusting handles 225, and are locked in position via their respective locking nuts 224. The one-dimensional rotary stage 223 is adjusted to a one-dimensional angle within the range of 0° to 360° via its corresponding adjusting handle 225, and is locked in position via its corresponding locking nut 224. Since the locking mechanism between the locking nut 224 and the adjusting handle 225 is prior art, it will not be described in detail here.

[0083] As an optional implementation, the absolute position target 23 is made of hard alloy steel and is cubic in shape. The absolute position target 23 possesses good geometrical accuracy, dimensional accuracy, and surface quality. All surfaces are smooth, flat, and uniformly textured matte surfaces, and all edges are sharp and straight, without chamfers or blunting. During the imaging process of the industrial camera 15, a two-dimensional image of the object being measured is formed by projecting a three-dimensional scene onto a two-dimensional image plane, resulting in the loss of spatial depth information. Therefore, standard spheres or similar objects with three-dimensional spatial characteristics are unsuitable as reference datums for the five-axis image coordinate measuring device 1. Since the output of the industrial camera 15 is a two-dimensional image of the object being measured, and it is sensitive to abrupt changes such as edges and sharp corners, a reference datum needs to be set according to its own characteristics to determine and set a specific datum in the five-axis image coordinate measuring device 1. Therefore, designing the absolute position target 23 as a cubic structure is preferred.

[0084] As an optional implementation, the five-axis image coordinate measuring device with an absolute position target also includes a target device protective cover 3, which is mounted on the worktable 11 and covers the target device 2.

[0085] Specifically, such as Figure 7 As shown, the target device protective cover 3 is used for dustproofing, impact protection, collision protection, and protection of the target device 2. The target device 2 is located inside the target device protective cover 3 and has no contact with any of the inner surfaces of the target device protective cover 3. The target device protective cover 3 can cover the target device 2 from five directions: above, left, right, front, and rear.

[0086] As an optional implementation, the target device protective cover 3 is a transparent cubic hollow shell. This design facilitates observation and confirmation of the target device 2's status.

[0087] As an optional implementation, a window 311 is provided on the front surface 31 of the protective cover 3 of the target device protective cover 3.

[0088] Specifically, such as Figure 7As shown, a window 311 is provided on the front surface 31 of the protective cover so that the industrial camera 15 can observe the front surface 231 of the absolute position target, the upper edge 234 of the absolute position target and the front edge 235 of the absolute position target.

[0089] As an optional implementation, the industrial camera 15 includes an industrial camera 151, a telecentric lens 152, and a light source 153. The telecentric lens 152 is mounted in the lens interface at the front end of the industrial camera 151, and the light source 153 is mounted at the front end of the telecentric lens 152.

[0090] Specifically, such as Figure 2 As shown, the industrial camera 15 is the front-end sensor of the five-axis image coordinate measuring device 1. It is mounted on the Z-axis moving end of the three-coordinate moving platform 14 through a mounting base, and the imaging optical axis direction of the industrial camera 15 is made parallel to the X-axis direction of the three-coordinate moving platform 14 through mechanical adjustment.

[0091] As an optional implementation, the light source 153 is an LED ring light source. The LED ring light source has a wide illumination area, ensuring that the lighting requirements of the industrial camera 151 are met.

[0092] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0093] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A method for determining the position of a rotation axis using an absolute position target, characterized in that, A five-axis image coordinate measuring device with an absolute position target includes a five-axis image coordinate measuring device (1), a target device (2) installed on the five-axis image coordinate measuring device (1), and a target device protective cover (3). The five-axis image coordinate measuring device (1) includes a worktable (11), a dual-axis rotary table (12), a clamping fixture (13), a three-coordinate moving platform (14), and an industrial camera (15). The dual-axis rotary table (12) and the three-coordinate moving platform (14) are both installed on the worktable (11). The clamping fixture (13) is installed on the table surface of the dual-axis rotary table (12). The industrial camera (15) is installed on the Z-axis moving end of the three-coordinate moving platform (14). The target device (2) includes an absolute position target (23). The method includes the following steps: Adjust the spatial attitude of the absolute position target (23); The relative positions between the absolute position target (23) and the dual-axis rotary table (12) are determined, and the front surface (231), side surface (233), and upper surface (232) of the absolute position target are respectively aligned with the pitch coordinate system O. B -X B Y B Z B Origin B and azimuth coordinate system O C -X C Y C Z C Origin C Spacing ΔX in the X, Y, and Z axes BS and ΔX CS ΔY BS and ΔY CS ΔZ BS and ΔZ CS ; Move the industrial camera (15), and when the front surface (231) of the absolute position target is on the object-side focal plane of the industrial camera (15), determine the reference coordinate system O based on the grating ruler reading of the X-axis linear motion. S -X S Y S Z S Origin O S X S0 Coordinate components; Lock the X-axis and move the industrial camera (15) along the Y-axis. When the front edge (235) of the absolute position target appears in the field of view of the industrial camera (15), determine the reference coordinate system O based on the grating ruler reading of the Y-axis linear motion axis and the pixel distance between the image coordinates of the front edge (235) of the absolute position target and the image center coordinates. S -X S Y S Z S Origin O S Y S0 Coordinate components; Lock the X-axis and move the industrial camera (15) along the Z-axis. When the edge (234) on the absolute position target appears in the field of view of the industrial camera (15), determine the reference coordinate system O based on the grating ruler reading of the Z linear motion axis and the pixel distance between the image coordinates of the edge (234) on the absolute position target and the image center coordinates. S -X S Y S Z S Origin O S Z S0 Coordinate components; Based on ΔX BS and ΔX CS ΔY BS and ΔY CS ΔZ BS and ΔZ CS and X S0 Coordinate components, Y S0 Coordinate components, Z S0 Coordinate components are used to obtain the position O of the rotation axis of the dual-axis rotary table (12). B and O C .

2. The method for determining the position of the rotation axis using an absolute position target according to claim 1, characterized in that, The adjustment of the spatial attitude of the absolute position target (23) is specifically as follows: After powering on and returning to zero, the target device (2) is installed on the workbench (11), and the spatial attitude and orientation of the absolute position target (23) are adjusted so that the front surface (231) of the absolute position target is parallel to the YOZ plane and the upper surface (232) of the absolute position target is parallel to the XOY plane, thus fixing the state of the absolute position target (23) and keeping it unchanged.

3. The method for determining the position of the rotation axis using an absolute position target according to claim 1, characterized in that, The target device (2) further includes a base (21) and an attitude adjustment mechanism (22). The base (21) is fixed on the worktable (11), the attitude adjustment mechanism (22) is installed on the base (21), and the absolute position target (23) is fixed on the attitude adjustment mechanism (22).

4. The method for determining the position of the rotation axis using an absolute position target according to claim 3, characterized in that, The attitude adjustment mechanism (22) includes a one-dimensional tilting stage A (221), a one-dimensional tilting stage B (222), a one-dimensional rotary stage (223), multiple locking nuts (224) and multiple adjustment handles (225), and the absolute position target (23) is installed on the one-dimensional rotary stage (223); The one-dimensional tilting stage A (221) and the one-dimensional tilting stage B (222) are stacked and installed in sequence and are respectively used to adjust the rotation angle α of the absolute position target (23) around the X axis and the rotation angle β around the Y axis under the drive of the corresponding adjustment handle (225), and are locked in position by the corresponding locking nut (224). The one-dimensional rotary table (223) is superimposed on the one-dimensional oscillating table A (221) or the one-dimensional oscillating table B (222) and is used to adjust the rotation angle γ of the absolute position target (23) around the Z-axis under the drive of the corresponding adjustment handle (225), and to lock the position by the corresponding locking nut (224).

5. The method for determining the position of the rotation axis using an absolute position target according to claim 3, characterized in that, The absolute position target (23) is made of hard alloy steel and is cubic in shape.

6. The method for determining the position of the rotation axis using an absolute position target according to claim 1, characterized in that, The five-axis image coordinate measuring device with an absolute position target also includes a target device protective cover (3), which is installed on the worktable (11) and covers the target device (2).

7. The method for determining the position of the rotation axis using an absolute position target according to claim 6, characterized in that, The protective cover (3) of the target device is a transparent cubic hollow shell.

8. The method for determining the position of the rotation axis using an absolute position target according to claim 6 or 7, characterized in that, The protective cover (3) of the target device has a window (311) on the front surface (31) of the protective cover.

9. The method for determining the position of the rotation axis using an absolute position target according to claim 1, characterized in that, The industrial camera (15) includes an industrial camera (151), a telecentric lens (152), and a light source (153). The telecentric lens (152) is installed in the lens interface at the front end of the industrial camera (151), and the light source (153) is installed at the front end of the telecentric lens (152).

10. The method for determining the position of the rotation axis using an absolute position target according to claim 9, characterized in that, The light source (153) is an LED ring light source.

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